1. Field of the Invention
The invention relates to novel substituted piperidines, to processes for preparation thereof, to the use thereof for treatment and/or prophylaxis of diseases and to the use thereof for production of medicaments for treatment and/or prophylaxis of diseases, especially of cardiovascular disorders and tumour disorders.
2. Description of the Prior Art
Thrombocytes (blood platelets) are a significant factor both in physiological haemostasis and in thromboembolic disorders. In the arterial system in particular, platelets are of central importance in the complex interaction between blood components and the wall of the vessel. Unwanted platelet activation may, through formation of platelet-rich thrombi, result in thromboembolic disorders and thrombotic complications with life-threatening conditions.
One of the most potent platelet activators is the blood coagulation protease thrombin, which is formed at injured blood vessel walls and which, in addition to fibrin formation, leads to the activation of platelets, endothelial cells and mesenchymal cells (Vu T K H, Hung D T, Wheaton V I, Coughlin S R, Cell 1991, 64, 1057-1068). In platelets in vitro and in animal models, thrombin inhibitors inhibit platelet aggregation and the formation of platelet-rich thrombi. In man, arterial thromboses can be prevented or treated successfully with inhibitors of platelet function and thrombin inhibitors (Bhatt D L, Topol E J, Nat. Rev. Drug Discov. 2003, 2, 15-28). Therefore, there is a high probability that antagonists of thrombin action on platelets will reduce the formation of thrombi and the occurrence of clinical sequelae such as myocardial infeaction and stroke. Other cellular effects of thrombin, for example on endothelial cells and smooth-muscle cells of vessels, on leukocytes and on fibroblasts, are possibly responsible for inflammatory and proliferative disorders.
At least some of the cellular effects of thrombin are mediated via a family of G-protein-coupled receptors (Protease Activated Receptors, PARs), the prototype of which is the PAR-1 receptor. PAR-1 is activated by bindung of thrombin and proteolytic cleavage of its extracellular N-terminus. The proteolysis exposes a new N-terminus having the amino acid sequence SFLLRN . . . , which, as an agonist (“tethered ligand”) leads to intramolecular receptor activation and transmission of intracellular signals. Peptides derived from the tethered-ligand sequence can be used as agonists of the receptor and, on platelets, lead to activation and aggregation. Other proteases are likewise capable of activating PAR-1, including, for example, plasmin, factor VIIa, factor Xa, trypsin, activated protein C (aPC), tryptase, cathepsin G, proteinase 3, granzyme A, elastase and matrix metalloprotease 1 (MMP-1).
In contrast to the inhibition of protease activity of thrombin with direct thrombin inhibitors, blockade of PAR-1 should result in an inhibition of platelet activation without reduction of the coagulability of the blood (anticoagulation).
Antibodies and other selective PAR-1 antagonists inhibit the thrombin-induced aggregation of platelets in vitro at low to medium thrombin concentrations (Kahn M L, Nakanishi-Matsui M, Shapiro M J, Ishihara H, Coughlin S R, J. Clin. Invest. 1999, 103, 879-887). A further thrombin receptor with possible significance for the pathophysiology of thrombotic processes, PAR-4, was identified on human and animal platelets. In experimental thromboses in animals having a PAR expression pattern comparable to humans, PAR-1 antagonists reduce the formation of platelet-rich thrombi (Derian C K, Damiano B P, Addo M F, Darrow A L, D'Andrea M R, Nedelman M, Zhang H-C, Maryanoff B E, Andrade-Gordon P, J. Pharmacol. Exp. Ther. 2003, 304, 855-861).
In the last few years, a large number of substances have been examined for their platelet function-inhibiting action; but only a few platelet function inhibitors have been found to be useful in practice. There is therefore a need for pharmaceuticals which specifically inhibit an increased platelet reaction without significantly increasing the risk of bleeding, and hence reduce the risk of thromboembolic complications.
Effects of thrombin which are mediated via the PAR-1 receptor affect the progression of disease during and after coronary artery bypass graft (CABG) and other operations and especially operations with extracorporeal circulation (for example heart-lung machine). During the course of the operation, there may be bleeding complications owing to pre- or intraoperative medication with coagulation-inhibiting and/or platelet-inhibiting substances. For this reason, for example, medication with clopidogrel has to be interrupted several days prior to a CABG. Moreover, as mentioned, disseminated intravascular coagulation or consumption coagulopathy (DIC) may develop (for example owing to the extended contact between blood and synthetic surfaces in the case of use of extracorporeal circulation or during blood transfusions), which in turn can lead to bleeding complications. Later, there is frequently restenosis of the venous or arterial bypasses grafted (which may even result in occlusion) owing to thrombosis, intimafibrosis, arteriosclerosis, angina pectoris, myocardial infarction, heart failure, arrhythmias, transitory ischaemic attack (TIA) and/or stroke.
In man, the PAR-1 receptor is also expressed in other cells including, for example, endothelial cells, smooth muscle cells and tumour cells. Malignant tumour disorders (cancer) have a high incidence and are generally associated with high mortality. Current therapies achieve full remission in only a fraction of patients and are typically associated with severe side effects. There is therefore a great need for more effective and safer therapies. The PAR-1 receptor contributes to cancer generation, growth, invasiveness and metastasis. Moreover, PAR-1 expressed on endothelial cells mediates signals resulting in vascular growth (“angiogenesis”), a process which is vital for allowing a tumour to grow larger than about 1 mm3. Angiogenesis also contributes to the genesis or worsening of other disorders including, for example, haematopoetic cancer disorders, macular degeneration, which leads to blindness, and diabetic retinopathy, inflammatory disorders, such as rheumatoid arthritis and colitis.
Sepsis (or septicaemia) is a frequent disorder with high mortality. Initial symptoms of sepsis are typically unspecific (for example fever, reduced general state of health); however, there may later be generalized activation of the coagulation system (“disseminated intravascular coagulation” or “consumption coagulopathy” (DIC)) with the formation of microthrombi in various organs and secondary bleeding complications. DIC may also occur independently of a sepsis, for example in the course of operations or in the event of tumour disorders.
Treatment of sepsis consists firstly in the rigorous elimination of the infectious cause, for example by operative removal of the focus and antibiosis. Secondly, it consists in temporary intensive medical support of the affected organ systems. Treatments of the different stages of this disease have been described, for example, in the following publication (Dellinger et al., Crit. Care Med. 2004, 32, 858-873). There are no proven effective treatments for DIC.